Contact cooling and mounting device for a discharge tube



Nqv. 4, 1969 F. POTZL 3,476,177

CONTACT COOLING AND MOUNTING DEVICE FOR A DISCHARGE TUBE Filed Feb. 5. 196B INVENTOR. FRIEDRIGI POTZL imk AG United States Patent 3,476,177 CONTACT COOLING AND MOUNTING DEVICE FOR A DISCHARGE TUBE Friedrich Potzl, Hamburg, Germany, assignor, by mesne assignments, to US. Philips Corporation, New York, N.Y., a corporation of Delaware Filed Feb. 5, 1968, Ser. No. 702,980 Claims priority, application Germany, Feb. 16, 1967, P 41,425 Int. Cl. F281? 7/00 U.S. Cl. 16580 ABSTRACT OF THE DISCLOSURE A tube holder and cooling wall are attached as a unit in a housing; the unit can be withdrawn from the housing through an opening in the housing wall. When the unit is in an operative position, the cooling wall serves to seal the opening in the housing wall and at the same time is designed to dissipate heat generated by a tube in the holder.

The invention relates to a cooling device for cooling electric discharge tubes by heat conduction (contact cooling). This device comprises a metal body which is in the form of a tube holder and is briefly termed tube holder in the following description, and a cooling wall which is detachably secured to this tube holder and forms part of a cabinet or a housing.

The invention consequently relates to a contact cooler for electric discharge tubes. These contact coolers are particularly suitable for use in mobile transmitters, since they do not require a blower so that the transmitter consumes less energy and may be of lighter weight. Moreover, no dust is introduced into the housing during the operation of the transmitter.

The construction and the operation of such contact coolers are quite different from those of the coolers used, for example, for travelling wave tubes. The latter coolers consist of fins which are directly secured on the tube. Such a known cooling device has been described in US. Patent 2,937,309.

It is known to arrange discharge tubes using contact cooling together with the circuitry in a completely closed housing which is provided on the outer side with cooling fins. In the known devices, the tube holder is screwed to the inner side of the housing with the interposition of an electrically insulating and thermally good conducting intermediate member. This tube holder is provided with means, for example a clamping block, for fixing the discharge tube. This clamping block comprises a body which is generally made of copper and is provided with a hole for receiving the anode of the discharge tube and with a slot extending from the edge of the hole as far as the edge of the body. In a direction at right angles to this gap, bolts are screwed into the clamping block, by means of which the anode of the tube can be clamped in the hole. When the assembly is manufactured with a suflicient accuracy, a reliable and thermally goOd conducting contact with the tube is then obtained.

According to British patent specification 953,381 a cooling device is secured to a discharge tube by means of rings which are radially slotted and have conical outer surfaces. Such rings are not used in contact coolers, however. The contact coolers for discharge tubes known hitherto have the disadvantage that great difiiculty is involved in removing the tube from the housing, since the housing is generally accessible only on one side. It is not easy either to mount the tube in the housing. These difiiculties especially arise in mobile transmitters for aero- Claims Patented Nov. 4, 1969 planes and the like which are of very compact construction and preferably use contact cooling.

These disadvantages are avoided when using the invention. The invention relates to a cooling device of the kind described above and is characterized in that the cooling wall forms with the body constructed as a tube holder a unit which is detachably secured to the housing and can be withdrawn from the housing in one direction together with the discharge tube through an opening in this housing.

According to the invention, the whole unit can be withdrawn from the housing by detaching a few screws or other securing means, even when the tubes are still hot, for example, in order to test the unit. The device according to the invention has the particular advantage that the cooling wall and the tube holder together with the discharge tube can be dismounted as a unit so that all the parts are readily accessible.

According to an embodiment of the invention, the outer side of the cooling wall is provided with cooling fins. An airtight packing may be disposed between the cool-ing wall and the housing so that the housing is completely closed, as is usual. Alternatively, an electrically conducting packing may be disposed between the cooling wall and the housing. Furthermore, according to the invention, an electrically insulating and thermally good conducting intermediate member may be provided between the cooling wall and the tube holder. This intermediate member may consist of a plate of boron nitride, aluminium oxide or beryllium oxide. The use of such a plate is known per se but hitherto the plate could be arranged in the housing only with difficulty. Particular steps were required to hold the intermediate member of generally complicated form in place until the securing screws for the tube holder have been tightened. In the device according to the invention, this disadvantage is avoided, because the whole unit can be assembled outside the housing. The body construction as a tube holder is provided with means for fixing the discharge tube. According to the invention, these means comprise an axially slotted clamping ring which is adapted to the discharge tube and may be inserted into the body and may expand in radial direction due to the presence of the slot. The conical inner surface of a ring screw slides over the likewise conical outer surface of the clamping ring, which ring screw is screwed into the body and thus tightens the clamping ring.

Due to this mode of securing, the discharge tube can be readily exchanged whilst moreover a reliable electrically and thermally good conducting contact is obtained. In order to further improve the heat conduction, a known paste may be provided between the surface sliding one over the other, which ensures that a satisfactory electric contact and a satisfactory heat dissipation are obtained; this is of great importance for the cooling of the discharge tube.

The invention will now be described more fully with reference to the accompanying drawing, which shows an embodiment.

A clamping ring 2 is slipped over the outer wall of the anode of a discharge tube 1. This clamping ring 2 may expand in radial direction, since the ring is provided with axially extending slots. These slots extend in the direction of the temperature gradient so that they do not disturb the heat dissipation. The conical inner surface 4 of a screw ring 5 slides over the likewise conical outer surface 3 of the clamping ring 2. This screw ring is screwed into the metal body 6 constructed as a tube holder. The screwthread 7 of the screw ring 5 and that of the body 6 and also the surface of the clamping ring 2 may be provided with a known paste ensuring a reliable electric contact and a satisfactory heat conduction.

The body 6 is in thermally good conducting contact with a plateor disc-shaped intermediate member of boron nitride (BN), aluminium oxide (A1 or beryllium oxide (BeO). The front surface of the intermediate member 8 engages the cooling wall 9 proper which is joined by means of screws 10 to the body 6 in the form of a tube holder. The thermally good conducting plate 8 consisting, for example, of beryllium oxide constitutes an electric insulation between the tube holder 6 and the cooling wall 9. A voltage of, for example, 3000 v. is applied between these two parts. In order to prevent shortcircuit via the securing screws, insulating sleeves 11 are arranged in the tapped holes of the tube holder 6.

The front side of the cooling wall 9 is provided with cooling fins 12 and 13 which are relatively offset. Consequently, an air current can pass between the fins 12 and 13 in the direction at right angles to the plane of the drawing. The cooling wall 9 is secured to the housing 14 by means of screws 15. The housing 14 must be provided with sufiiciently large holes 16 so that the screws may be readily inserted and the expansion of the housing 14 due to the developed heat may be neutralized. The cooling wall 9 is secured on the housing by means of screws and nuts 17.

In accordance with the prevailing conditions, the cooling wall 9 can be secured to the housing 14 in different ways. For example, an electrically insulating packing 18 such as a metal wire gauze or an air-tight packing 19, also referred to as pneumatic packing, may be used. Furthermore, a second air-tight packing 20 tightly surrounding the screw 15 may be provided sothat a dusttight closure of the housing is obtained.

The cooling wall 9 may have an angular or a circular form.

The device has the advantage that, after the screws 15 have been removed, the unit comprising the cooling wall, the tube holder 6 and the discharge tube can be withdrawn from and inserted into the housing in one direction and by one manipulation. The separate parts can be assembled outside the housing, which results in a considerable simplification of the manufacture of such a cooling device. The cooling wall is placed on a horizontal table, for example, with its front side directed downwards, whereupon the intermediate member 8, the body 6 constructed as a tube holder and the discharge tube 1 are secured. It is easy to check whether the parts are relatively correctly orientated and the assembly can be tested so that the unit need only be inserted into the housing which is generally fixedly arranged. This provides a simplification of the maintenance of devices already arranged, in which it is of particular importance that the tubes can be rapidly exchanged. The units are suitable for various kinds of tubes, since the parts can be exchanged within a comparatively short time.

What is claimed is:

1. A device for mounting a discharge tube with-in a wall enclosed housing and providing external cooling therefor comprising:

a cooling wall,

a tube holder attached to the cooling wall,

an intermediate member positioned between the tube holder and cooling wall and forming an integral unit therewith which permits the passage of heat by conduction from the tube holder to the cooling wall; a clamping ring located in the tube holder and adapted to be placed around a discharge tube in the area of the anode and in thermal contact with the tube, and means for detachably securing the tube holder and attached tube, within the housing through an opening in the wall of the housing so that the cooling wall completely seals the opening and when the cooling wall is removed, the discharge tube will be withdrawn therewith from the housing. 2. The device as claimed in claim 1 wherein the cooling wall has plurality of fins projecting in a direction away from the housing.

3. The device as claimed in claim 2 wherein an electrically insulating packing is placed between the cooling wall and the wall of the housing.

4. The device as claimed in claim 3 wherein the intermediate member is a plate of a material selected from the group consisting of boron nitride, aluminum oxide and beryllium oxide.

5. The device as claimed in claim 4 wherein the clamping ring is axially slotted to permit radial expansion due to heating; and further comprising:

a screw ring surrounding and in sliding contact with the clamping ring, and threaded into the tube holder,

whereby the clamping ring will secure a discharge tube in the tube holder and conduct heat away from the discharge tube.

References Cited UNITED STATES PATENTS 2,730,663 1/ 1956 Harty -186 2,751,528 6/1956 Burton 165-186 2,942,165 6/ 1960 Jackson et al. 165-74 3,261,904 7/1966 Wulc 165-80 3,369,597 2/1968 Drousuth et al. 165-80 ROBERT A. OLEARY, Primary Examiner CHARLES SUKALO, Assistant Examiner US. Cl. X.R. 165-186 

